‍ ‍The Tortuga Charitable Foundation was started in 1980 by Joan Livingston Tweedy and her children who are dedicated to environmental protection and women’s health issues. With Joan's passing in 2018, her children and grandchildren continue her legacy.

We do our best to adhere to the following practices:

  • Build capacity of organizations in the field.

    Tortuga seeks to balance funding smaller locally-focused groups with supporting established organizations that serve the broader field;

  • Provide general support grants whenever possible.

    More flexibility is good for everyone.

  • Bet on leaders.

    Philanthropy can play a useful role in identifying strong leaders and giving them the capacity they need to run with a vision.

Our Team

Karen Harris with brown hair smiling, wearing earrings, a necklace, and a blue-green patterned scarf.

Karen Harris

Executive Director

Karen Harris has served as Executive Director of the Tortuga Charitable Foundation since 2022. Before joining Tortuga, Karen was Program Director of the Clean Energy Program at the John Merck Fund, which supported state and regional climate and clean energy policies with a focus on promoting renewable energy, stopping fossil fuel infrastructure, and facilitating transportation electrification.

For over twenty years, Karen managed a consulting practice providing strategic planning, grants management, facilitation, and evaluation to foundations and non-profit organizations. During that time Karen worked with organizations that included Energy Innovation, Energy Foundation, Heising-Simons Foundation, Barr Foundation, EcoHealth Network, Rockefeller Family Fund, Doris Duke Charitable Foundation, Land Trust Alliance, and Alaskans for Energy Freedom. Prior to her work as a consultant, Karen was a Program Officer in the Conservation Program at the Packard Foundation and Executive Director of the Ploughshares Fund.

Karen currently serves on the board of the Biodiversity Funders Group and on the Steering Committee of the Climate and Energy Funders Group. She holds a BS in environmental law and policy from the University of California at Berkeley.

Lucy Winikoff with dark curly hair, smiling, wearing a patterned burgundy top with red and blue accents, against a plain gray background.

Lucy Winikoff

Grants Manager and Program Officer

Lucy Winikoff has served as Tortuga Charitable Foundation’s Grants Manager and Program Officer since 2023. Prior to joining Tortuga, Lucy was an Associate Director at Arabella Advisors, a philanthropic consulting firm. While at Arabella, she helped family foundations and individual donors with grantmaking, strategy development, and foundation operations. Lucy also previously served as Program Services Coordinator for a nonprofit organization that provides support to families navigating childhood cancer. Lucy holds a BA in history from Rice University.

Gregory Horner wearing a blue shirt, dark vest, and khaki pants crouches in a grassy outdoor field with trees in the background.

Gregory Horner

Program Consultant

Gregory Horner has been part of the Tortuga Charitable Foundation team since 2024. He has worked in the environmental field for 28 years, and at the intersection of environment, agriculture, energy, and sustainability for 21 years. As an independent consultant Greg works with foundations, nonprofits, and individual donors, providing strategy development, research, impact assessment, and program implementation. He has worked with the Cedar Tree Foundation, TomKat Ranch Educational Foundation, Patagonia, and the Sunrise Project.